Benefits of Short Interimplant Delays in Children Receiving Bilateral Cochlear Implants

Relationships between bilateral auditory brainstem activity and inter-implant interval in children with cochlear implants

PURPOSE

To investigate the effect of the interval between bilateral cochlear implantation on the development of bilateral peripheral auditory pathways as revealed by the electrically evoked auditory brainstem response (EABR).

METHODS

Fifty-eight children with profound bilateral sensorineural hearing loss were recruited. Among them, 33 children received sequential bilateral cochlear implants (CIs), and 25 children received simultaneous bilateral CIs. The bilateral EABRs evoked by electrical stimulation from the CI electrode were recorded on the day of second-side CI activation.

RESULTS

The latencies of wave III (eIII) and wave V (eV) were significantly shorter on the first CI side than on the second CI side in children with sequential bilateral CIs but were similar between the two sides in children with simultaneous bilateral CIs. Furthermore, the latencies were prolonged from apical to basal channels along the cochlea in the two groups. In children with sequential CIs, the inter-implant interval was negatively correlated with the eV latency on the first CI side and was positively correlated with bilateral differences in the eIII and eV latencies.

CONCLUSIONS

Unilateral CI use promotes the maturation of ipsilateral auditory conduction function. However, a longer inter-implant interval results in more unbalanced development of bilateral auditory brainstem pathways. Bilateral cochlear implantation with no or a short interval is recommended.

Long-term effects of second cochlear implantation with sequential bilateral cochlear implantation in Japanese children

OBJECTIVE

This study aimed to longitudinally evaluate speech perception ability and sound-field thresholds with the first, second, or bilateral cochlear implants (CIs) and MAP parameters of second CI in children.

METHODS

Eighteen children who underwent bilateral cochlear implantation at Kyoto University Hospital were included. We evaluated speech perception under quiet and noisy conditions using the first, second, or bilateral CIs, CI-aided sound-field thresholds using the first or second CI, and MAP parameter values (C-levels, T-levels, and dynamic range) of the second CI of more than 5 years after the second implantation.

RESULTS

Patients with a second CI after 7 years of age had significantly worse speech perception ability with the second CI even long after the surgery than those with a second CI before 7 years of age. CI-aided sound-field thresholds using the first or second CI were similar, regardless of the second implantation timing. Speech perception in noise with bilateral CIs was enhanced by the addition of a second CI, even after 7 years of age. Patients undergoing second cochlear implantation before 3.5 years of age showed significantly higher C-levels and wider dynamic ranges in the second CI MAP parameters.

CONCLUSIONS

When the second implantation was performed after 7 years of age, the second CI effects were limited even with long-term use, which is attributed to unstable MAP parameters. The second CI-aided sound-field threshold contributed to the better outcome of bilateral CIs in noise, even if the second implantation was performed at age of ≥7 years.

[Word production in children with cochlear implant based on chronological age and hearing age]

BACKGROUND

For congenitally deaf children, an early bilateral provision with cochlear implant (CI) is a favourable condition for language acquisition. The objective of the present study was to determine the word production in CI children. The focus was on a comparison of chronological age and hearing age performance and on the evaluation of potential effects of multilingualism, additional disabilities and age at provision.

METHODS

The data of 62 children with bilateral CI (age at provision in months M=12,1; SD=6,2) were retrospectively analysed. Vocabulary was assessed by the test Aktiver Wortschatztest für 3- bis 5-jährige Kinder - Revision and compared for chronological age and hearing age. Group comparisons and correlation analysis was conducted regarding multilingualism, additional disabilities and age at provision.

RESULTS

The cohort performed significantly better when referenced to hearing age: level were within or above the norm in more than 50%; referenced to chronological age in around 37%. The descriptive performance differences for multilingualism and additional disabilities were only significant for children with both characteristics. Performance of monolingual children without additional disabilities was not significantly associated with age at provision.

CONCLUSION

CI children may achieve an adequate expressive vocabulary at the age of 3 to 5 years. Multilingualism and additional disabilities seem to be particular challenges for CI children and need a more precise definition in further studies. The use of both chronological and hearing age as reference marks allows a differentiated assessment of the language status. This may lead to benefits in therapeutic interventions and parent councelling.

A Modified Pediatric Ranked Order Speech Perception Score to Assess Speech Recognition Development in Children With Cochlear Implants

PURPOSE

Characterizing and comparing speech recognition development in children with cochlear implants (CIs) is challenging because of variations in test type. This retrospective cohort study modified the Pediatric Ranked Order Speech Perception (PROSPER) scoring system to (a) longitudinally analyze the speech perception of children with CIs and (b) examine the role of age at CI activation, listening mode (i.e., unilateral or bilateral implantation), and interimplant interval.

METHOD

Postimplantation speech recognition scores from 31 children with prelingual, severe-to-profound hearing loss who received CIs were analyzed (12 with unilateral CI [UniCI], 13 with sequential bilateral CIs [SEQ BiCIs], and six with simultaneous BiCIs). Data were extracted from the Massachusetts Eye and Ear Audiology database. A version of the PROSPER score was modified to integrate the varying test types by mapping raw scores from different tests into a single score. The PROSPER scores were used to construct speech recognition growth curves of the implanted ears, which were characterized by the slope of the growth phase, the time from activation to the plateau onset, and the score at the plateau.

RESULTS

While speech recognition improved considerably for children following implantation, the growth rates and scores at the plateau were highly variable. In first implanted ears, later implantation was associated with poorer scores at the plateau (β = -0.15, p = .01), but not growth rate. The first implanted ears of children with BiCIs had better scores at the plateau than those with UniCI (β = 0.59, p = .02). Shorter interimplant intervals in children with SEQ BiCIs promoted faster speech recognition growth of the first implanted ears.

CONCLUSION

The modified PROSPER score could be used clinically to track speech recognition development in children with CIs, to assess influencing factors, and to assist in developing and evaluating patient-specific intervention strategies.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.20113538.

Comparison of Outcomes in Unilateral and Bilateral Pediatric Cochlear Implants: Our Experience

The aim of our study is to compare the outcomes in unilateral and bilateral cochlear implants in pediatric age and also between simultaneous and sequential cochlear implant surgery. This retrospective study was carried out with 83 children aged between 12 months to 2.5 years which included 41 children with bilateral Cochlear implants and 42 with unilateral implants. Out of these 41 children, 21 were simultaneous and 20 were sequential cochlear implant. All the children were operated at civil hospital Gandhinagar, Gujarat, India. CAP, SIR, localization, traffic noise and speech in noise scores were assessed at regular intervals over the period of 4 years. Also the drug administration time, surgical time, operating room time were assessed for simultaneous and sequential cochlear implant surgery. Children with bilateral simultaneous implants fared significantly better with CAP, SIR, localization, speech noise and traffic noise scores than sequential bilateral implants and unilateral implants with a significant difference of means t tests between the two groups. Simultaneous cochlear implant surgery is associated with reduced surgical time, operating room time, it shortens the total in patient stay. There is less of drug administration and bilateral ones are stimulated simultaneously. Bilateral cochlear implants perform better with respect to auditory perception skills and spontaneous speech when compared with unilateral implants, but simultaneous surgery is better and safe option for pediatric cochlear implantation.

Effects of Sequential Bilateral Cochlear Implantation in Children: Evidence from Speech-Evoked Cortical Potentials and Tests of Speech Perception

INTRODUCTION

Benefits of bilateral cochlear implants (CI) may be compromised by delays to implantation of either ear. This study aimed to evaluate the effects of sequential bilateral CI use in children who received their first CI at young ages, using a clinical set-up.

METHODS

One-channel cortical auditory evoked potentials and speech perception in quiet and noise were evoked at repeated times (0, 3, 6, 12 months of bilateral CI use) by unilateral and bilateral stimulation in 28 children with early-onset deafness. These children were unilaterally implanted before 3.69 years of age (mean ± SD of 1.98 ± 0.73 years) and received a second CI after 5.13 ± 2.37 years of unilateral CI use. Comparisons between unilaterally evoked responses were used to measure asymmetric function between the ears and comparisons between bilateral responses and each unilateral response were used to measure the bilateral benefit.

RESULTS

Chronic bilateral CI promoted changes in cortical auditory responses and speech perception performance; however, large asymmetries were present between the two unilateral responses despite ongoing bilateral CI use. Persistent cortical differences between the two sides at 1 year of bilateral stimulation were predicted by increasing age at the first surgery and inter-implant delay. Larger asymmetries in speech perception occurred with longer inter-implant delays. Bilateral responses were more similar to the unilateral responses from the first rather than the second CI.

CONCLUSION

These findings are consistent with the development of the aural preference syndrome and reinforce the importance of providing bilateral CIs simultaneously or sequentially with very short delays.

Receptive Vocabulary of Children With Bilateral Cochlear Implants From 3 to 16 Years of Age

OBJECTIVES

The vocabulary of children with cochlear implants is often smaller than that of their peers with typical hearing, but there is uncertainty regarding the extent of the differences and potential risks and protective factors. Some studies indicate that their receptive vocabulary develops well at first, but that they fail to keep up with their typical hearing peers, causing many CI users to enter school with a receptive vocabulary that is not age-appropriate. To better understand the receptive vocabulary abilities of children with cochlear implants this study explored age-related differences to matched children with typical hearing and associations between vocabulary skills and child-level characteristics.

DESIGN

A retrospective cross-sectional study with matched controls was conducted at the Norwegian national cochlear implant center at Oslo University Hospital. Eighty-eight children (mean age 8.7 years; range 3.2 to 15.9; 43 girls, 45 boys) who had received bilateral cochlear implants before 3 years of age were compared with two groups of children with typical hearing. One group was matched for maternal education, sex, and chronological age, the other group was matched for maternal education, sex, and hearing age. Receptive vocabulary performance was measured with the British Picture Vocabulary Scale.

RESULTS

Cochlear implant users' receptive vocabulary was poorer than that of age-matched children with typical hearing ( M = 84.6 standard points, SD = 21.1; children with typical hearing: M = 102.1 standard points, SD = 15.8; mean difference -17.5 standard points, 95% CI [-23.0 to -12.0], p < 0.001; Hedges's g = -0.94, 95% CI [-1.24 to -0.62]), and children with cochlear implants were significantly more likely to perform below the normative range (risk ratio = 2.2, 95% CI [1.42 to 3.83]). However, there was a significant nonlinear U-shaped effect of age on the scores of cochlear implant users, with the difference to the matched typical hearing children being largest (23.9 standard points, on average) around 8.7 years of age and smaller toward the beginning and end of the age range. There was no significant difference compared with children with typical hearing when differences in auditory experience were accounted for. Variability was not significantly different between the groups. Further analysis with a random forest revealed that, in addition to chronological age and hearing age, simultaneous versus sequential implantation, communication mode at school, and social integration were predictors of cochlear implant users' receptive vocabulary.

CONCLUSIONS

On average, the receptive vocabulary of children with cochlear implants was smaller than that of their typical hearing peers. The magnitude of the difference was changing with age and was the largest for children in early primary school. The nonlinear effect of age might explain some of the ambiguity in previous research findings and could indicate that better intervention is required around school entry. The results emphasize that continuous monitoring and support are crucial to avoid far-reaching negative effects on the children's development and well-being.

Factors Associated with Speech-Recognition Performance in School-Aged Children with Cochlear Implants and Early Auditory-Verbal Intervention

BACKGROUND

Considerable variability exists in the speech recognition abilities achieved by children with cochlear implants (CIs) due to varying demographic and performance variables including language abilities.

PURPOSE

This article examines the factors associated with speech recognition performance of school-aged children with CIs who were grouped by language ability.

RESEARCH DESIGN

This is a single-center cross-sectional study with repeated measures for subjects across two language groups.

STUDY SAMPLE

Participants included two groups of school-aged children, ages 7 to 17 years, who received unilateral or bilateral CIs by 4 years of age. The High Language group (N = 26) had age-appropriate spoken-language abilities, and the Low Language group (N = 24) had delays in their spoken-language abilities.

DATA COLLECTION AND ANALYSIS

Group comparisons were conducted to examine the impact of demographic characteristics on word recognition in quiet and sentence recognition in quiet and noise.

RESULTS

Speech recognition in quiet and noise was significantly poorer in the Low Language compared with the High Language group. Greater hours of implant use and better adherence to auditory-verbal (AV) therapy appointments were associated with higher speech recognition in quiet and noise.

CONCLUSION

To ensure maximal speech recognition in children with low-language outcomes, professionals should develop strategies to ensure that families support full-time CI use and have the means to consistently attend AV appointments.

Age-related language performance and device use in children with very early bilateral cochlear implantation

OBJECTIVES

Paediatric cochlear implantation within the first year of life results in better outcome in auditory and language skills. Beside individual, audiological and social factors, quantity and quality of daily cochlear implant (CI) use also seem to be an influencing factor. The purpose of this study was to evaluate children's early receptive and expressive language performance considering bilingual language development as well as quantity and quality of daily CI use and intraoperative objective measurements.

METHODS

The retrospective analysis included data from 35 very early bilaterally cochlear-implanted children (age at CI M = 8.4 ± 1.5 months). Language performance was assessed by the German standardised test SETK-2 (age at testing M = 29.4 ± 4.0 months). The CI system-integrated data-logging was analysed with regard to daily CoilOn-time, CoilOff and exposure to classified listening scenes. Intraoperatively measured thresholds of evoked compound action potentials (T-ECAPs) were analysed to ensure CI functionality.

RESULTS

The cohort showed language performance within the normal range for word comprehension, sentence comprehension and word production, level of sentence production was reduced. Overall, bilingual children performed less well than monolingual children. Intraoperative T-ECAPs were recorded for the total cohort and no anomalies were detected. Children used their CI for about 8.7 ± 1.4 h per day, most of this time spent in a quiet environment (38%). Word production was significantly correlated with the daily duration of CI use (CoilOn-time) and with exposure to the listening environment Speech. No correlation was found between number of daily coil disconnections (CoilOff) and language performance.

CONCLUSION

Very early bilateral cochlear implantation may result in age-appropriate language skills already at the age of 2 years. Monolingualism seems to a better condition for early language development with CI than bilingualism. Especially for word production, the daily duration of CI use and exposure time in a speech-characterised environment seem to be additional positive factors. Monitoring the data-logs should be one important focus of professionals during the postoperative rehabilitation process to detect potential benefits and risks. These findings should be integrated into rehabilitative therapy and parent counselling.

Effects of long-term unilateral cochlear implant use on large-scale network synchronization in adolescents

Unilateral cochlear implantation (CI) limits deafness-related changes in the auditory pathways but promotes abnormal cortical preference for the stimulated ear and leaves the opposite ear with little protection from auditory deprivation. In the present study, time-frequency analyses of event-related potentials elicited from stimuli presented to each ear were used to determine effects of unilateral CI use on cortical synchrony. CI-elicited activity in 34 adolescents (15.4±1.9 years of age) who had listened with unilateral CIs for most of their lives prior to bilateral implantation were compared to responses elicited by a 500Hz tone-burst in normal hearing peers. Phase-locking values between 4 and 60Hz were calculated for 171 pairs of 19-cephalic recording electrodes. Ear specific results were found in the normal hearing group: higher synchronization in low frequency bands (theta and alpha) from left ear stimulation in the right hemisphere and more high frequency activity (gamma band) from right ear stimulation in the left hemisphere. In the CI group, increased phase synchronization in the theta and beta frequencies with bursts of gamma activity were elicited by the experienced-right CI between frontal, temporal and parietal cortical regions in both hemispheres, consistent with increased recruitment of cortical areas involved in attention and higher-order processes, potentially to support unilateral listening. By contrast, activity was globally desynchronized in response to initial stimulation of the naïve-left ear, suggesting decoupling of these pathways from the cortical hearing network. These data reveal asymmetric auditory development promoted by unilateral CI use, resulting in an abnormally mature neural network.

Spatial Hearing Difficulties in Reaching Space in Bilateral Cochlear Implant Children Improve With Head Movements

Supplemental Digital Content is available in the text.

The aim of this study was to assess three-dimensional (3D) spatial hearing abilities in reaching space of children and adolescents fitted with bilateral cochlear implants (BCI). The study also investigated the impact of spontaneous head movements on sound localization abilities.

Factors affecting phoneme discrimination in children with sequential bilateral cochlear implants

OBJECTIVES

To investigate the effects of a number of variables on phoneme discrimination (PD) performance in children with sequential bilateral cochlear implants (SeqBiCIs) and compare PD performance between the 2 implantation sides and between children with bilateral cochlear implants (BiCIs) and their age-matched peers with normal hearing (NH).

DESIGN

All participants completed the Auditory Speech Sound Evaluation Phoneme Discrimination Test.

STUDY SAMPLE

The sample included 23 children with SeqBiCIs as the study group and 23 with NH as the control group.

RESULTS

A significant difference was found between the scores of the two groups under the CI₁ and CI₂ conditions (p = 0.001), CI₁ and BiCI conditions (p = 0.002), and CI₂ and BiCI conditions (p = 0.001). PD scores with CI₁ significantly depend on age at CI₁ and duration of bilateral use. PD scores with CI₁ were significant predictors of PD performance with CI₂. Duration of BiCI use was a significant predictor of PD scores with BiCI.

CONCLUSIONS

The age at CI₁ and the duration of bilateral cochlear implant use were found to improve phoneme discrimination performance in children with a sequential bilateral cochlear implant. According to the success of the CI₁, it is possible to predict the success of CI₂ use.

Meta-Analytic Findings on Reading in Children With Cochlear Implants

This meta-analysis study aims to quantify the group differences in reading skills between children with cochlear implants and their hearing peers and between children with cochlear implants and children with hearing aids (aged between 3 and 18 years old). Of the 5,642 articles screened, 47 articles met predetermined inclusion criteria (published between 2002 and 2019). The robust variance estimation based meta-analysis models were used to synthesize all the effect sizes. Children with cochlear implants scored significantly lower than their hearing peers in phonological awareness (g = -1.62, p < 0.001), vocabulary (g = -1.50, p < 0.001), decoding (g = -1.24, p < 0.001), and reading comprehension (g = -1.39, p < 0.001), but not for fluency (g = -0.67, p = 0.054). Compared to children with hearing aids, children with cochlear implants scored significantly lower in phonological awareness (g = -0.30, p = 0.028). The percentage of unilateral cochlear implant negatively impacts the group difference between children with cochlear implants and their hearing peers. Findings from this study confirm a positive shift in reading outcomes for profoundly deaf children due to cochlear implantation. Some children with cochlear implants may need additional supports in educational settings.

Effect of unilateral cochlear implant use on contralateral electrically evoked auditory brainstem responses to round window membrane electrical stimulation

BACKGROUND

Long-term use of a unilateral cochlear implant (CI) may lead to abnormal development of contralateral auditory pathway.

OBJECTIVES

To investigate the usefulness of measuring the electrically evoked auditory brainstem response (eABR) with the electrical stimulation at the round window membrane and the effect of unilateral CI use on the contralateral auditory pathway functions.

MATERIALS AND METHODS

According to duration of unilateral CI use, 45 children with severe or profound sensorineural hearing loss were divided into sCI (≤12 months), lCI (≥24 months) and nCI (no CI use) groups. Intra-operative eABRs evoked by electrical stimulation at the round window membrane were recorded.

RESULTS

The latencies of eIII and eV were significantly longer in lCI group than in sCI group and in nCI group, respectively, but not significantly different between sCI group and nCI group. The eABR thresholds and eIII-eV latency intervals were not significantly different among three groups.

CONCLUSIONS AND SIGNIFICANCE

The eABR evoked by the electrical stimulation at the round window membrane is a reliable and effective way of evaluating functions of the auditory pathway in deaf children. Long-term use of a unilateral CI may promote the degenerative process of the contralateral auditory pathway to the level of the brainstem.

Bilateral cochlear implantation in children: simultaneously or in consecutive sessions?

OBJECTIVE

This study aimed to evaluate and compare cases of simultaneous and consecutive bilateral cochlear implantation from the perspective of the duration of anaesthesia, surgical complications and hospitalisation.

METHOD

Fifty patients with simultaneous bilateral cochlear implantation (group 1) and 47 patients with consecutive bilateral cochlear implantation (group 2) were included in this study. The two groups were compared in terms of the duration of anaesthesia, the duration of surgery, radiological findings, the complications and the post-operative hospitalisation time.

RESULTS

Group 1 had a significantly shorter operation time than group 2 (p < 0.01). The mean total operation time was 189 minutes in group 1. In group 2, the mean operation times for the first and second surgery were 134 minutes and 136 minutes, respectively, and the total operation time for both surgical procedures in group 2 was 270 minutes. The duration of post-operative hospitalisation of the patients in group 1 was significantly shorter than the total post-operative hospitalisation after both operations for the patients in group 2 (p < 0.01).

CONCLUSION

In conclusion, if there is no anatomical problem that may lead to a prolonged operation time or any risk regarding anaesthesia, simultaneous bilateral cochlear implantation can be performed safely.

Bilateral Cochlear Implants or Bimodal Hearing for Children with Bilateral Sensorineural Hearing Loss

Purpose of review

This review describes speech perception and language outcomes for children using bimodal hearing (cochlear implant (CI) plus contralateral hearing aid) as compared to children with bilateral CIs and contrasts said findings with the adult literature. There is a lack of clinical evidence driving recommendations for bimodal versus bilateral CI candidacy and as such, clinicians are often unsure about when to recommend a second CI for children with residual acoustic hearing. Thus the goal of this review is to identify scientific information that may influence clinical decision making for pediatric CI candidates with residual acoustic hearing.

Recent findings

Bilateral CIs are considered standard of care for children with bilateral severe-to-profound sensorineural hearing loss. For children with aidable acoustic hearing-even in just the low frequencies-an early period of bimodal stimulation has been associated with significantly better speech perception, vocabulary, and language development. HA audibility, however, is generally poorer than that offered by a CI resulting in interaural asymmetry in speech perception, head shadow, as well as brainstem and cortical activity and development. Thus there is a need to optimize "two-eared" hearing while maximizing a child's potential with respect to hearing, speech, and language while ensuring that we limit asymmetrically driven auditory neuroplasticity. A recent large study of bimodal and bilateral CI users suggested that a period of bimodal stimulation was only beneficial for children with a better-ear pure tone average (PTA) ≤ 73 dB HL. This 73-dB-HL cutoff applied even to children who ultimately received bilateral CIs.

Summary

Though we do not yet have definitive guidelines for determining bimodal versus bilateral CI candidacy, there is increasing evidence that 1) bilateral CIs yield superior outcomes for children with bilateral severe-to-profound hearing loss and, 2) an early period of bimodal stimulation is beneficial for speech perception and language development, but only for children with better-ear PTA ≤ 73 dB HL. For children with residual acoustic hearing, even in just the low-frequency range, rapid sequential bilateral cochlear implantation following a trial period with bimodal stimulation will yield best outcomes for auditory, language, and academic development. Of course, there is also an increasing prevalence of cochlear implantation with acoustic hearing preservation allowing for combined electric and acoustic stimulation even following bilateral implantation.

The outcomes of bilateral cochlear implant users in Universiti Kebangsaan Malaysia

INTRODUCTION

Bilateral cochlear implants are seen to improve hearing capabilities.

OBJECTIVE

To assess the auditory outcome of paediatric bilateral cochlear implant in Universiti Kebangsaan Malaysia.

MATERIALS AND METHODS

This was a cross-sectional and descriptive study single centre analysis. Categories of Auditory Performance (CAP-II) scale and Speech, Spatial and Qualities (SSQ) of Hearing questionnaire were used.

RESULTS

Forty-six patients were recruited. Majority of the children (30.4%) rated 7 and 23.9% scored perfectly (9) based on the CAP-II Scale. The least performing children were rated 5 (average). Children that were implanted sequentially within 24 months showed median CAP-II scale of 7. No significant correlation seen between CAP-II and the duration interval, use and age of 1st CI (p > .05). The speech domain of SSQ-P scale showed median value of 8 indicating good speech understanding. The spatial hearing domain had median value of 7, quality of hearing domain had median of 8. Significant correlation seen in hearing in noise with the duration of use of CI (p < .05).

DISCUSSION

Bilateral CI have shown benefits in auditory performance even though majority were performed sequentially. Promising outcome was better with prolonged usage of the device.

CONCLUSION

Hearing in noise is significantly better in bilateral CI.

Sequential Bilateral Cochlear Implantation With Prolonged Time Intervals

Purpose The aim of the study was to assess whether sequential cochlear implantation (CI) with a prolonged interimplant interval (M = 15.2 years) between the first and second CIs benefited speech recognition and health-related quality of life. Method This prospective study included 14 prelingually deafened participants who received their second CI after a prolonged interimplant interval (M = 15.2 years). Additionally, speech recognition ability over a 12-month period of bilateral implant use was investigated. The results of the speech recognition test in both quiet and noisy conditions were statistically analyzed for each CI alone and both CIs together. Nijmegen Cochlear Implant Questionnaire scores were also collected at activation and at 12 months after activation. Results Improvements in speech recognition ability were observed following the use of the first implant alone and with the use of both implants together; however, progress was much slower with the use of the second implant alone, following its introduction. Furthermore, a significant difference in the trajectory of speech recognition ability was observed between the first and the second implanted ear. According to Nijmegen Cochlear Implant Questionnaire scores, all participants benefitted from bilateral CI after 12 months. Conclusions Prolonged interimplant intervals resulted in asymmetrical speech recognition abilities. A significant improvement in the speech recognition scores was observed with the first implanted ear, and much slower progress was observed with the second implanted ear. However, the "poorer" second implanted ear could provide a considerable beneficial effect on the improved speech recognition and health-related quality of life with the bilateral CI. Supplemental Material https://doi.org/10.23641/asha.12861152.

Hearing and speech benefits of cochlear implantation in children: A review of the literature

Cochlear implantation is a safe and reliable treatment for children with severe to profound hearing loss. The primary benefit of these medical devices in children is the acquisition of hearing, which promotes development of spoken language. The present paper reviews published literature demonstrating predictive effects of a number of factors on acquisition of hearing development and speech recognition. Of the many variables that contribute to an individual child's development after implantation, age at implantation, the presence of medical comorbidities, social determinants of health, and the provision of bilateral versus unilateral hearing are those that can vary widely and have consistently shown clear impacts. Specifically, age of implantation is crucial to reduce effects of deafness on the developing auditory system and capture the remarkable plasticity of early development. Language development after cochlear implantation requires therapy emphasizing hearing and oral communication, education, and other support which can be influenced by known social determinants of health; specifically, outcomes in children decline with reductions in socioeconomic status and levels of parental education. Medical co-morbidities also slow rates of progress after cochlear implantation. On the other hand, benefits of implantation increase in children who are provided with access to hearing from both ears. In sum, cochlear implants promote development of hearing in children and the best outcomes are achieved by providing early access to sound in both ears. These benefits can be limited by known social determinants of health which restrict access to needed support and medical comorbidities which add further complexity in care and outcome.

The Effect of Cochlear Implant Interval on Spoken Language Skills of Pediatric Bilateral Cochlear Implant Users

OBJECTIVE

To examine the effects of cochlear implant (CI) interval (time between CI surgeries) on receptive vocabulary and receptive language skills for children with bilateral CIs.

STUDY DESIGN

A prospective cross-sectional study design.

SETTING

Participants were recruited from, and tested at, oral schools for the deaf and pediatric audiology clinics across the United States.

PATIENTS

Eighty-eight children, 4 to 9 years of age, with bilateral CIs and known hearing histories. Twenty-three participants received CIs simultaneously and 65 received CIs sequentially. Of those implanted sequentially, 86% wore a hearing aid (HA) on the non-implanted ear during the CI interval.

INTERVENTION

Bilateral cochlear implantation.

MAIN OUTCOME MEASURES

Receptive vocabulary was measured via the Peabody Picture Vocabulary Test (PPVT). Receptive language skills were measured via the Clinical Evaluation of Language Fundamentals (CELF).

RESULTS

Multiple linear regression models indicate better receptive vocabulary and receptive language skills are associated with earlier ages at first CI (CI 1), but not with shorter CI intervals.

CONCLUSIONS

Early cochlear implantation (i.e., age at CI 1) is critical for better receptive vocabulary and receptive language skills. Shorter CI intervals are not associated with better receptive vocabulary and receptive language skills for these 88 children, who nearly all used bimodal hearing during the interval. Use of a HA at the non-implanted ear, before receipt of a second CI (CI 2), may mitigate the effects of early bilateral auditory deprivation.

Benefit and predictive factors for speech perception outcomes in pediatric bilateral cochlear implant recipients

INTRODUCTION

Despite recent advancement in the prediction of cochlear implant outcome, the benefit of bilateral procedures compared to bimodal stimulation and how we predict speech perception outcomes of sequential bilateral cochlear implant based on bimodal auditory performance in children remain unclear.

OBJECTIVES

This investigation was performed: (1) to determine the benefit of sequential bilateral cochlear implant and (2) to identify the associated factors for the outcome of sequential bilateral cochlear implant.

METHODS

Observational and retrospective study. We retrospectively analyzed 29 patients with sequential cochlear implant following bimodal-fitting condition. Audiological evaluations were performed; the categories of auditory performance scores, speech perception with monosyllable and disyllables words, and the Korean version of Ling. Audiological evaluations were performed before sequential cochlear implant with the bimodal fitting condition (CI1+HA) and one year after the sequential cochlear implant with bilateral cochlear implant condition (CI1+CI2). The good performance group (GP) was defined as follows; 90% or higher in monosyllable and bisyllable tests with auditory-only condition or 20% or higher improvement of the scores with CI1+CI2. Age at first implantation, inter-implant interval, categories of auditory performance score, and various comorbidities were analyzed by logistic regression analysis.

RESULTS

Compared to the CI1+HA, CI1+CI2 provided significant benefit in categories of auditory performance, speech perception, and Korean version of Ling results. Preoperative categories of auditory performance scores were the only associated factor for being GP (odds ratio=4.38, 95% confidence interval - 95%=1.07-17.93, p=0.04).

CONCLUSIONS

The children with limited language development in bimodal condition should be considered as the sequential bilateral cochlear implant and preoperative categories of auditory performance score could be used as the predictor in speech perception after sequential cochlear implant.

Critical Factors for Binaural Hearing in Children with Bilateral Sequential Cochlear Implantation: First Implant Performance and Inter-Implant Interval

Objectives: This study evaluated the influence of the performance of the first cochlear implant (CI-1) on the second implant (CI-2) and the significance of inter-implant intervals in children with sequential cochlear implantation. Method: Thirty-four patients were included for speech perception outcome and 38 patients were included for subjective hearing satisfaction in daily life in this study. The patients were classified into 3 groups according to inter-implant interval: group I, <4 years; group II, 4–7 years; group III, >7 years. Open-set speech perception scores before and at 3, 6, 12, and 24 months after the second implantation was compared among the CI-1, CI-2, and bilateral CI conditions. Subjective hearing benefits in daily life were measured using a questionnaire of Speech, Spatial, and Qualities of Hearing Scale (SSQ) for parents of children with impaired hearing, and device use and preference were evaluated (by phone interview.) Results: The speech perception of children using the CI-2 only improved quickly within 3 months postoperatively and were similar to those using the CI-1 only. The results of monosyllabic and disyllabic word tests using CI-2 at 3 months after second implantation were not significantly different from those in patients using the CI-1 only. In the sentence test, the scores using the CI-2 only were not significantly different from those using the first implant only at 6 months after second implantation. SSQ scores were similar among groups and the worst score in each section was shown from the questions about performance under noisy conditions in each section. Device usage habits showed that 17 (44.7%) and 16 (42.1%) patients preferred bilateral and the CI-1, respectively. Only 5 (13.2%) patients wanted the CI-2 rather than the CI-1. While group I and II showed a prominent positive attitude to bilateral use, group III, for which the inter-implant interval was 7 years or more, showed a definite preference for the CI-1 (p < 0.01). Conclusions: Functional binaural benefits were achieved in patients who were good performers with the CI-1 after the second implantation irrespective of the inter-implant interval. Sequential CI should be strongly recommended for patients with unilateral CI showing a good performance.

Somatosensory Cross-Modal Reorganization in Children With Cochlear Implants

Deprived of sensory input, as in deafness, the brain tends to reorganize. Cross-modal reorganization occurs when cortices associated with deficient sensory modalities are recruited by other, intact senses for processing of the latter's sensory input. Studies have shown that this type of reorganization may affect outcomes when sensory stimulation is later introduced via intervention devices. One such device is the cochlear implant (CI). Hundreds of thousands of CIs have been fitted on people with hearing impairment worldwide, many of them children. Factors such as age of implantation have proven useful in predicting speech perception outcome with these devices in children. However, a portion of the variance in speech understanding ability remains unexplained. It is possible that the degree of cross-modal reorganization may explain additional variability in listening outcomes. Thus, the current study aimed to examine possible somatosensory cross-modal reorganization of the auditory cortices. To this end we used high density EEG to record cortical responses to vibrotactile stimuli in children with normal hearing (NH) and those with CIs. We first investigated cortical somatosensory evoked potentials (CSEP) in NH children, in order to establish normal patterns of CSEP waveform morphology and sources of cortical activity. We then compared CSEP waveforms and estimations of cortical sources between NH children and those with CIs to assess the degree of somatosensory cross-modal reorganization. Results showed that NH children showed expected patterns of CSEP and current density reconstructions, such that postcentral cortices were activated contralaterally to the side of stimulation. Participants with CIs also showed this pattern of activity. However, in addition, they showed activation of auditory cortical areas in response to somatosensory stimulation. Additionally, certain CSEP waveform components were significantly earlier in the CI group than the children with NH. These results are taken as evidence of cross-modal reorganization by the somatosensory modality in children with CIs. Speech perception in noise scores were negatively associated with CSEP waveform components latencies in the CI group, suggesting that the degree of cross-modal reorganization is related to speech perception outcomes. These findings may have implications for clinical rehabilitation in children with cochlear implants.

Cortical auditory evoked responses in cochlear implant users with early-onset single-sided deafness: indicators of the development of bilateral auditory pathways

Cochlear implantation (CI) for early-onset single-sided deafness (SSD) provides a unique insight into the development and cortical reorganization of binaural pathways. This case series aimed to investigate the impact of duration of deafness on CI outcomes as measured by cortical evoked auditory potentials (CAEPs). Four adults with early-onset SSD were studied after CI. The adults had a duration of deafness of 22, 24, 42, and 38 years before implantation. CAEPs and speech perception in noise were used to investigate binaural cortical pathways and function. Our four patients lost their hearing at the ages of 3, 6, 5, and 6 (S1, S2, S3, and S4, respectively). CAEPs were present bilaterally in S2, S3, and S4. S1's, who had the least experience with a CI, cortical responses at 1 month after CI activation showed cortical responses from the CI ipsilateral pathway, but no responses from the CI contralateral pathway. At 3 and 6 months, S1 showed significant cortical responses from the CI contralateral pathway for two speech tokens. An improvement in speech perception in noise testing was observed in all four participants. This case series indicates that long duration of deafness for early-onset SSD is not a contraindication for CI and may not impact the long-term outcomes in this population. The electrical stimulation from the CI integrates with the normal-hearing ear to produce bilateral cortical projections and functional improvement in speech perception in noise. These early data provide surprisingly positive results and call for larger scale research to be carried out.

Categories of Auditory Performance and Speech Intelligibility Ratings in Prelingually Deaf Children With Bilateral Implantation

Purpose The aim of the current study was to review all pediatric cases with congenital deafness who underwent bilateral implantation in our center. Specifically, auditory performance and speech intelligibility ratings were compared across children based on their mode of bilateral stimulation (simultaneous or sequential implantation). Method A retrospective chart review design was used in this study. A total of 46 congenitally deaf children were included. Children ranged in age between 2 and 8 years, with a mean of 3 years 7 months. Participants were divided into 2 groups: those who received their bilateral implant simultaneously and those who received them sequentially. Categories of Auditory Performance (CAP; Archbold, Lutman, & Marshall, 1995 ) scores and Speech Intelligibility Rating (SIR; M. C. Allen, Nikolopoulos, & O'Donoghue, 1998 ) scores were used to measure their performance. Results Children scored an average of 4.1 (±1.6) on the CAP Scale and 1.6 (±1) on the SIR Scale. Results showed that children who received their implants simultaneously scored relatively higher on the CAP Scale than those with sequential implants. However, there were no differences between the 2 groups in SIR scores. These 2 outcome measures were not correlated with age at implantation. Conclusion The current study demonstrated that simultaneous implantation could potentially improve audiologic outcome.

Limiting asymmetric hearing improves benefits of bilateral hearing in children using cochlear implants

Neurodevelopmental changes occur with asymmetric hearing loss, limiting binaural/spatial hearing and putting children at risk for social and educational challenges. These deficits may be mitigated by providing bilateral hearing in children through auditory prostheses. Effects on speech perception and spatial hearing were measured in a large cohort of >450 children who were deaf and used bilateral cochlear implants or bimodal devices (one cochlear implant and a contralateral hearing aid). Results revealed an advantage of bilateral over unilateral device use but this advantage decreased as hearing in the two ears became increasingly asymmetric. Delayed implantation of an ear with severe to profound deafness allowed asymmetric hearing, creating aural preference for the better hearing ear. These findings indicate that bilateral input with the most appropriate device for each ear should be provided early and without delay during development.

Speech Detection in Noise for Young Bilaterally Implanted Children: Is There Evidence of Binaural Benefit Over the Shadowed Ear Alone?

OBJECTIVES

To measure binaural benefit over the shadowed ear alone for young bilateral cochlear implant (CI) users. It was hypothesized that children who received bilateral CIs at a young age (<4 years), and had significant bilateral experience, would demonstrate lower detection thresholds for speech sounds in background noise in the bilateral CI over the unilateral CI condition when the added CI was ipsilateral to the noise source.

DESIGN

Children receiving bilateral CIs at the Eye and Ear Hospital Clinic in Melbourne were invited to participate in a wider research project evaluating outcomes; those participating in the wider project who were bilaterally implanted by 4 years and were approximately 2 years postoperative were included in the present study. For 20 participants, detection signal to noise ratios (SNRs) were measured for speech presented from in front and noise from 90° in at least 3 of 4 device/noise conditions, namely left CI/noise right and right CI/noise left, plus bilateral CIs/noise right and bilateral CIs/noise left.

RESULTS

As some participants could only complete testing in 3 conditions within the 1 test block, the unilateral versus bilateral comparison was performed for 1 CI (i.e., 1 noise direction) for 15 participants and for both CIs (i.e., noise left and noise right) for 5 participants. Group analysis indicated no significant difference in detection SNR between the unilateral and bilateral CI conditions when adding the left CI or right CI (for the overall group) or when adding the first or second CI (for the 15 participants with sequential bilateral CIs). Separate analyses indicated no significant difference in detection SNR between the unilateral and bilateral CI conditions for the majority of individuals; this occurred irrespective of whether the analysis indicated that the CI added in the bilateral condition was poorer-performing, better-performing, or not significantly different compared with the other CI. Four individuals demonstrated a significant improvement in the bilateral condition when the CI added in the bilateral condition was a better-performing (n = 1), poorer-performing (n = 2), or not significantly different CI (n = 1). There was no relationship between the detection SNR difference between each CI and the detection SNR difference between the unilateral and bilateral conditions.

CONCLUSIONS

The hypothesis of a lower detection SNR in the bilateral condition was not supported by the group results or by the results for the majority of individuals. For the 4 participants who did demonstrate benefit over the shadowed ear alone, that benefit cannot be separated from the potential benefit gained as a result of the CI added in the bilateral condition being the better-performing CI for 1 of the 4. Variation in outcomes could not be related to demographic factors for this group, which was relatively homogeneous for age at bilateral CI and experience; an older, more experienced group may demonstrate greater binaural benefit in these conditions. These results can be used during counseling for families regarding postoperative expectations for young children, especially in the first 2 years.

P1 cortical auditory evoked potential in children with unilateral or bilateral cochlear implants; implication for the timing of second cochlear implantation

OBJECTIVE

To examine maturation of the central auditory pathway, using P1 cortical auditory evoked potential (CAEP), in children who had received unilateral or bilateral cochlear implantation (CI).

STUDY DESIGN

Prospective study.

SETTING

Tertiary referral hospital.

METHODS

Twenty children who had received CI due to congenital, or prelingual, deafness participated in the study. Participants had received the 1st implant at a mean age of 3.4 ± 0.7 years; 16 had also received a 2nd CI for the contralateral ear, at a mean age of 11.1 ± 2.1 years. P1 CAEP was recorded while using the 1st implant and, for those who received contralateral CI, within 2 weeks of switching on the 2nd implant. Relations between P1 latency and duration with the 1st implant, and between age at 1st CI and P1 latency, were investigated. Relations between P1 latency with the 1st and 2nd implants, and between the interstage interval and difference between P1 latencies with the 1st and 2nd implants, were also examined.

RESULTS

P1 CAEP with the 1st implant was present in 16 of the 20 children. Mean P1 latency was shorter in the early CI group compared with the late CI group, but this difference was not statistically significant (p = 0.154). There was a significant negative correlation between the duration with the 1st implant and P1 latency (r = - 0.783, p < 0.001). Among the 16 children with sequential bilateral CI, P1 CAEP with the 2nd implant was present in 10. There was a significant negative correlation between the duration with the 1st implant before receiving the 2nd implant and P1 latency with the 2nd implant (r = - 0.710, p = 0.021); there was also a significant positive correlation between P1 latency with the 1st and 2nd implants (r = 0.722, p = 0.018). There was not a significant correlation between interstage interval and the difference between the two P1 latencies (r = - 0.430, p = 0.248).

CONCLUSION

Longer cochlear implant use is associated with shorter P1 latency. Unilateral hearing with the 1st implant may positively affect P1 latency with the 2nd CI ear. These findings imply that increased auditory experience may influence central auditory pathway maturation and that the degree of central auditory pathway maturation before the 2nd CI, rather than the timing when the surgery is received, may influence 2nd CI outcome in children with sequential bilateral cochlear implants.

Perceived improvements and challenges following sequential bilateral cochlear implantation in children and adults

OBJECTIVE

Semi-structured interviews were conducted with sequentially implanted bilateral cochlear-implant (biCI) recipients to examine functional aspects of communication that are affected by listening with one versus two CIs.

DESIGN

Participants were 15 adult biCI recipients and parents of 30 children (categorized into three groups by age) with biCIs. All CI users had sequential placement of biCIs with at least six months' experience with the first CI before activation of the second device, and at least three months' experience with both CIs prior to the interview. The parent/paediatric and adult interviews were all conducted by the same examiner. Electronic transcripts of the interview responses were coded for perceived changes or lack thereof in 23 behaviours following biCI. Extent of reported benefit was quantified for each subject within and across these behaviours and at the group level as a function of age.

RESULTS

Most adults and parents of children reported multiple functional changes following biCI use, and changes often translated to enhanced social communication. Nearly all participants were consistent users of biCIs, and were satisfied with their perceived gains in communicating in everyday settings. Most reported ongoing challenges listening in noisy settings. Although many reports on children paralleled those of adults, developmental differences were apparent. Thirteen percent of adults and twenty percent of parents of children in each of the respective groups reported low levels of change.

CONCLUSIONS

Results suggest that many biCI users experience meaningful functional benefits that may be underestimated by traditional outcome measures. We suggest the need to expand measurement approaches to better quantify the nature of these benefits.

Cortical organization restored by cochlear implantation in young children with single sided deafness

Early treatment of single sided deafness in children has been recommended to protect from neurodevelopmental preference for the better hearing ear and from social and educational deficits. A fairly homogeneous group of five young children (≤3.6 years of age) with normal right sided hearing who received a cochlear implant to treat deafness in their left ears were studied. Etiology of deafness was largely cytomegalovirus (n = 4); one child had an enlarged vestibular aqueduct. Multi-channel electroencephalography of cortical evoked activity was measured repeatedly over time at: 1) acute (0.5 ± 0.7 weeks); 2) early chronic (1.1 ± 0.2 months); and 3) chronic (5.8 ± 3.4 months) cochlear implant stimulation. Results indicated consistent responses from the normal right ear with marked changes in activity from the implanted left ear. Atypical distribution of peak amplitude activity from the implanted ear at acute stimulation marked abnormal lateralization of activity to the ipsilateral left auditory cortex and recruitment of extra-temporal areas including left frontal cortex. These abnormalities resolved with chronic implant use and contralateral aural preference emerged in both auditory cortices. These findings indicate that early implantation in young children with single sided deafness can rapidly restore bilateral auditory input to the cortex needed to improve binaural hearing.

Sequential pediatric bilateral cochlear implantation: The effect of time interval between implants

OBJECTIVE

To examine speech intelligibility in children subjected to sequential bilateral cochlear implants (CI) surgery and to assess the influence of the inter-stage interval duration.

INTRODUCTION

Binaural hearing recovery can have additional benefits, especially in speech and language development in patients with congenital profound sensorineural hearing loss; so recently there has been an increase in the number of children receiving bilateral CI.

METHODS

Twenty-seven children who underwent sequential bilateral cochlear implant (SBCI) with a short (1-3 yrs), medium (4-6 yrs) and long (7-12 yrs) range interval between both implantations, respectively, were evaluated. All patients underwent periodic speech perception test in quiet and noise after second implant activation in three conditions: with the first or second implant alone and with both implants. Results were examined according to the inter-stage interval.

RESULTS

Speech intelligibility in noise was significantly better under bilateral conditions than either ear alone, in all three groups. Small improvements were seen in quiet, especially in the third group (6-12 yrs).

CONCLUSION

Benefits of second implant in the early-implanted children and after a short inter-implant delay are more evident. However our study support that, even after a long period of deafness and despite a prolonged inter-stage interval, sequential bilateral cochlear implantation should be considered.

LEVEL OF EVIDENCE

Level 4.

Music perception improves in children with bilateral cochlear implants or bimodal devices

The objectives of this study were to determine if music perception by pediatric cochlear implant users can be improved by (1) providing access to bilateral hearing through two cochlear implants or a cochlear implant and a contralateral hearing aid (bimodal users) and (2) any history of music training. The Montreal Battery of Evaluation of Musical Ability test was presented via soundfield to 26 bilateral cochlear implant users, 8 bimodal users and 16 children with normal hearing. Response accuracy and reaction time were recorded via an iPad application. Bilateral cochlear implant and bimodal users perceived musical characteristics less accurately and more slowly than children with normal hearing. Children who had music training were faster and more accurate, regardless of their hearing status. Reaction time on specific subtests decreased with age, years of musical training and, for implant users, better residual hearing. Despite effects of these factors on reaction time, bimodal and bilateral cochlear implant users' responses were less accurate than those of their normal hearing peers. This means children using bilateral cochlear implants and bimodal devices continue to experience challenges perceiving music that are related to hearing impairment and/or device limitations during development.

Simultaneous bilateral cochlear implants: Developmental advances do not yet achieve normal cortical processing

BACKGROUND

Simultaneous bilateral cochlear implantation promotes symmetric development of bilateral auditory pathways but binaural hearing remains abnormal. To evaluate whether bilateral cortical processing remains impaired in such children, cortical activity to unilateral and bilateral stimuli was assessed in a unique cohort of 16 children who received bilateral cochlear implants (CIs) simultaneously at 1.97 ± 0.86 years of age and had ~4 years of CI experience, providing the first opportunity to assess electrically driven cortical development in the absence of reorganized asymmetries from sequential implantation.

METHODS

Cortical activity to unilateral and bilateral stimuli was measured using multichannel electro-encephalography. Cortical processing in children with bilateral CIs was compared with click-elicited activity in 13 normal hearing children matched for time-in-sound. Source activity was localized using the Time Restricted, Artefact and Coherence source Suppression (TRACS) beamformer method.

RESULTS

Consistent with dominant crossed auditory pathways, normal P1 activity (~100 ms) was weaker to ipsilateral stimuli relative to contralateral and bilateral stimuli and both auditory cortices preferentially responded to the contralateral ear. Right hemisphere dominance was evident overall. Children with bilateral CIs maintained the expected right dominance but differences from normal included: (i) minimal changes between ipsilateral, contralateral and bilateral stimuli, (ii) weaker than normal contralateral stimulus preference, (iii) symmetric activity to bilateral stimuli, and (iv) increased occipital lobe recruitment during bilateral relative to unilateral stimulation. Between-group contrasts demonstrated lower than normal activity in the inferior parieto-occipital lobe (suggesting deficits in sensory integration) and greater than normal left frontal lobe activity (suggesting increased attention), even during passive listening.

CONCLUSIONS

Together, findings suggest that early simultaneous bilateral cochlear implantation promotes normal-like auditory symmetry but that abnormalities in cortical processing consequent to deafness and/or electrical stimulation through two independent speech processors persist.

United Kingdom national paediatric bilateral project: Results of professional rating scales and parent questionnaires

OBJECTIVES

This fourteen-centre project used professional rating scales and parent questionnaires to assess longitudinal outcomes in a large non-selected population of children receiving simultaneous and sequential bilateral cochlear implants.

METHODS

This was an observational non-randomized service evaluation. Data were collected at four time points: before bilateral cochlear implants or before the sequential implant, one year, two years, and three years after. The measures reported are Categories of Auditory Performance II (CAPII), Speech Intelligibility Rating (SIR), Bilateral Listening Skills Profile (BLSP) and Parent Outcome Profile (POP).

RESULTS

Thousand and one children aged from 8 months to almost 18 years were involved, although there were many missing data. In children receiving simultaneous implants after one, two, and three years respectively, median CAP scores were 4, 5, and 6; median SIR were 1, 2, and 3. Three years after receiving simultaneous bilateral cochlear implants, 61% of children were reported to understand conversation without lip-reading and 66% had intelligible speech if the listener concentrated hard. Auditory performance and speech intelligibility were significantly better in female children than males. Parents of children using sequential implants were generally positive about their child's well-being and behaviour since receiving the second device; those who were less positive about well-being changes also generally reported their children less willing to wear the second device.

CONCLUSION

Data from 78% of paediatric cochlear implant centres in the United Kingdom provide a real-world picture of outcomes of children with bilateral implants in the UK. This large reference data set can be used to identify children in the lower quartile for targeted intervention.

Bilateral cochlear implants in children: Effects of auditory experience and deprivation on auditory perception

Spatial hearing skills are essential for children as they grow, learn and play. These skills provide critical cues for determining the locations of sources in the environment, and enable segregation of important sounds, such as speech, from background maskers or interferers. Spatial hearing depends on availability of monaural cues and binaural cues. The latter result from integration of inputs arriving at the two ears from sounds that vary in location. The binaural system has exquisite mechanisms for capturing differences between the ears in both time of arrival and intensity. The major cues that are thus referred to as being vital for binaural hearing are: interaural differences in time (ITDs) and interaural differences in levels (ILDs). In children with normal hearing (NH), spatial hearing abilities are fairly well developed by age 4-5 years. In contrast, most children who are deaf and hear through cochlear implants (CIs) do not have an opportunity to experience normal, binaural acoustic hearing early in life. These children may function by having to utilize auditory cues that are degraded with regard to numerous stimulus features. In recent years there has been a notable increase in the number of children receiving bilateral CIs, and evidence suggests that while having two CIs helps them function better than when listening through a single CI, these children generally perform worse than their NH peers. This paper reviews some of the recent work on bilaterally implanted children. The focus is on measures of spatial hearing, including sound localization, release from masking for speech understanding in noise and binaural sensitivity using research processors. Data from behavioral and electrophysiological studies are included, with a focus on the recent work of the authors and their collaborators. The effects of auditory plasticity and deprivation on the emergence of binaural and spatial hearing are discussed along with evidence for reorganized processing from both behavioral and electrophysiological studies. The consequences of both unilateral and bilateral auditory deprivation during development suggest that the relevant set of issues is highly complex with regard to successes and the limitations experienced by children receiving bilateral cochlear implants. This article is part of a Special Issue entitled .

Balancing current levels in children with bilateral cochlear implants using electrophysiological and behavioral measures

Children have benefited from bilateral cochlear implants (CIs) over unilateral CIs despite often missing important periods in bilateral auditory development. This suggests a remarkable perceptual ability by children to "work around" abnormal changes in the auditory pathways. Nonetheless, these children rely primarily on interaural level differences as interaural timing cues are more difficult to access or detect. Mismatched levels provided to the two implants could distort interaural level cues thus compromising the benefits of bilateral CI use. We asked whether "balanced" or "centered" perception of bilateral input can be predicted by physiological or behavioral measures. Twenty-four children who had used unilateral CIs for 9.21 ± 2.66 years prior to bilateral implantation participated. "Balanced bilateral levels" were identified by responses occurring with a probability of 50% on the right side of the head and 50% on the left in a two choice lateralization task. Loudness judgments of current presented unilaterally by each implant were measured on a continuous visual scale. Maximum wave eV amplitudes were evoked unilaterally by each implant and matched amplitudes were identified. Balanced bilateral levels were predicted within 10 Clinical Units (CU) in 9 of 13 (69%) children using matched wave eV amplitudes. Bilaterally balanced levels were reasonably predicted by similar loudness judgments (<10% difference between CIs) in only 6 of 13 (46%) children. Results indicate that matching amplitudes of physiological responses can produce a balanced perception of bilateral input despite unilateral strengthening of the auditory pathways and can potentially be used clinically to provide a first approximation of balance/centered levels.